Effects of oscillatory-pressure amplitude during dynamic sinter forging on the microstructure and mechanical properties of Al₂O₃–Ti(C,N)

High-performance Al₂O₃-Ti(C,N) composites are critical for extreme-environment applications, yet conventional static sintering cannot simultaneously achieve full densification and strong grain-boundary bonding. Here, a dynamic sinter forging (DSF) strategy coupling sintering densification and oscillatory forging deformation was developed to activate plastic flow and defect engineering. Composites were sintered at 1600 °C with oscillatory amplitudes of 0–40 MPa (5 Hz) and a maximum pressure of 80 MPa. The flexural strength increased from 583 MPa under a pressure of 80 ± 0 MPa to 1070 MPa under 40 ± 40 MPa, representing an 83 % enhancement. TEM revealed increased dislocation densities in Al₂O₃ (2.6 ×10⁵→2.9 ×10⁶ cm⁻²) and Ti(C,N) (4.8 ×10⁶→8.2 ×10⁶ cm⁻²) and curved interfaces, shifting fracture from intergranular to transgranular, showing that defect generation and interface curvature jointly strengthen the composites. This DSF route enables concurrent densification and microstructural strengthening within a single thermal cycle, offering a general pathway to high-toughness oxide–carbonitride ceramics.